Is Age 13 an Unlucky Number for Parents?

The fact that teen pregnancy is down means that adolescents know how to protect themselves against both pregnancy and disease, Lipsitt said.

Role Models, and Dinner Hour

Experts say that teens need role models, adults in their lives who set limits on their behavior, and that they also need a set academic or vocational path to help keep them on the straight and narrow.

"The more disorganized a family is, the more at risk the child," Lipsitt said. "If for example, the child has no meaningful dinner engagements with his own family, that child will be more likely to adopt risky behaviors."

In Thirteen, Tracy is raised by her single mother, played by Holly Hunter. Researchers still have not concluded what impact a single-parent home has on children's development, Lipsitt said.

But Leventhal said the number of parents involved in raising the child makes a huge difference.

"Being in a one-parent household is very hard for a parent, even if they are a good parent," Leventhal said. "Look at the time it takes for parenting and the pressure of parenting. One-parent families are more likely to have difficulties."

In three decades of working with teens, Leventhal said the biggest changes he has seen is that adults expect teens to act more like grown-ups than they ever had to before, and kids are exposed to more sexual imagery than previous generations were.

"There's a push toward having them behave more maturely than they can think," he said. "We let children dress and behave more like they're little adults, and they're not little adults. They're children."